Method and apparatus for drilling through soil and rock layers



April 21, 1970 F HAsr-:wr-:ND ETAL 3,507,342

METHOD AND APPARATUS FOR DRILLING THROUGH SOIL AND ROCK LAYERS 2 Sheets-Sheet 1 FlLed Feb. 27. 1967 April 2l, 1970 F. HKAsEwEND ETAL 3,507,342

METHOD AND APPARATUS FOR DRILLING THROUGH SOIL AND ROCK LAYERS 2 Sheets-Sheet 2 Filed Feb. 27, 196'? wm ...2f Wsw 465 H3 SH Sie @am United States Patent O 3,507,342 METHOD AND APPARATUS FOR DRILLING THROUGH SOIL AND ROCK LAYERS Florian Hasewend, Kapfenberg, Styria, Hubert Pichler, Bruck an der Mur, Styria, and Walter Mayerhofer, Kapfenberg, Styria, Austria, assgnors to Gebr. Bohler & Co. Aktiengesellschaft, Vienna, Austria Filed Feb. 27, 1967, Ser. No. 618,839 Claims priority, application Austria, Feb. 28, 1966, 1,828/ 66 Int. Cl. E21c 19/00; E21b 21/00, 9/22 U.S. Cl. 175--62 11 Claims ABSTRACT F THE DISCLOSURE The means which connect a cutter bit, generally hori zontal, to a string of drill pipes and dene apertures which communicate with the interior of the drill pipes and which receive material which has been detached by the bit and subject said material to the percussive movement of the assembly of drill pipes to cause the material to move through said apertures into and through the drill pipes, from which the material is discharged through lateral openings outside the borehole. The equipment is of special advantage in drilling through dams of rock or soil.

This invention relates to a method and apparatus for drilling preferably in a generally horizontal direction through soil and rock layers by means of a rotary an-d percussive drilling tool, e.g., a drill hammer, in which method the material to be removed is detached by a cutter bit and is removed through the drill pipes.

To form a duct through a dam or an elevation of the ground, it has previously been required to excavate a ditch down to the depth of the duct to be formed. The walls had to be properly supported to prevent the walls of the ditch from caving in.

The formation of a duct with the aid of drilling equipment and the support of the walls of the borehole by compacting the material was possible only in soil and rock layers which had a sutiiciently high inherent strength to prevent the duct from caving in before a subsequent compaction is effected.

These known methods cannot be used if the dam to be drilled through consists of layers of loose soil or rock or even of layers of coarse gravel because in such cases the duct would cave in immediately behind the cutter bit in most cases. It is particularly difcult to drill through dams in which `big stones are embedded in layers of loose soil or rock and these big stones must be drilled through.

To avoid the installation of an expensive supporting structure in drilling through dams with the aid of rotary and percussive tools according to the method of the invention, it is suggested to utilize the percussive action of the drill hammer for removing the disintegrated or detached material which has been excavated or the core material through the drill pipes and to discharge said material into the open through openings in the drill pipes outside the borehole. For this purpose a drill hammer is required which is provided with a rotary motor and has a strong percussive action and is advanced, e.g., by a chain along a mount to drive the drill pipes and the cutter bit into the borehole.

The invention `will now be explained with reference to embodiments shown by way of example in the drawing.

FIG. 1 shows drilling equipment having a step bit,

FIG. la is a sectional view taken on line I-I of FIG. 1 through the step bit,

FIG. 1b is an elevation of the rotary motor and percussion motor for actuating the drilling equipment.

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FIG. 2 shows drilling equipment provided with a step bit and a wash conduit,

FIG. 2a is a sectional View taken on line II-II of FIG. 2 through the shank of the cutter bit and FIG. 3 is a partial sectional elevation of a drilling equipment provided with a core bit. Y

The step bit shown in FIG. 1 comprises a starter bit 1 and an enlarging bit 2. The latter is formed in its peripheral surface with an annular groove 3, which is succeeded by two webs 4 connecting the drill bit to the cylindrical pipe 5. The outside diameter of the latter is approximately as large as the diameter of the end face of the enlarging bit. The webs 4 are provided with extensions 6, which are bent outwardly like blades and serve for pushing the material `which has been detached by the bits through the opening 7 between the webs 4 into the axial cavity 8 of the drill bit during the rotation of the latter. The periphery of the bit is provided with a smoothening bead 9, which has a diameter that is as large as the length of the cutting edge 0f the starter bit or is even somewhat larger than the diameter of the borehole and serves to compact and smoothen the wall 10 of the borehole.

The reduced end portion of the shank 5 of the bit is formed with a screw thread, which is screwed into a drill pipe 11. Any desired number of drill pipes may be connected to the drill pipe 11, depending on the progress of the borehole. An adapter 12 provided with a screw thread may be welded to the end of each drill pipe to provide a connection between each pipe and the succeeding one. The end pipe 13 disposed outside the borehole is formed in its periphery with sufficiently large openings 14, through which the excavated material is discharged out of the string of drill pipes. This end pipe is connected by the connector 15 to the drill rod 16, which connects the drilling tool to a rotary motor 26 and a percussion drive 25.

This drilling tool has the following mode of operation.

The drilling tool is rotated by a strong motor about its longitudinal axis and percussions in the axial direction are continually applied to the drilling tool by a second motor. The loosening and detaching of material from the face of the borehole is mainly effected by the rotation and assisted by the percussions. This material flows between the bits of the tool to the apertures 7 between the webs 4 and is pushed by the bladelike extensions 6 into the cavity 8 of the drill pipe 11. Under the continual axial percussions, the excavated material is moved through the drill pipe 11 and any further drill pipes as though it were conveyed on vibratory chutes, and after reaching the end pipe 13 falls out of the same through the openings 14 owing to the rotation of the pipe. The axial movement and the disintegration of the excavated material by the drill pipe or pipes is promoted by the rotary motion so that even moist or caking material can be conveyed and ejected without trouble.

FIG. 2 shows also -a drilling tool comprising a step bit which is similar to that of FIG. l. This tool differs from that of FIG. 1 by a wash conduit, which extends through the drill pipe 11 and through the Idrill bits 2 and 1. T0 hold the wash pipe 17 in the drill pipe 11, through which the excavated material flows, adapters 12 are inserted between the drill pipes and provided with webs 19 holding hubs Ztl, in which the wash pipe is anchored. Under the .percussive action, the excavated material travels through all drill pipes and falls out through the opening-s 23 of the end pipe 21, which is disposed outside the borehole. In this arrangement, the removal of cuttings from the face of the borehole and the removal of the excavated material from the borehole is promoted by the washing action of the washing fluid.

FIG. 3 shows a modified embodiment, in which the drill pipes 11 are connected by adapters 12 and a core bit 22 is connected to the end of the drill pipes. The periphery of the -rear part of the bit is stepped and is about as large in diameter as the forward part of the core bit and is screw-connected to the drill pipe 11,A which is also approximately as large in diameter as the bit. That part of the drill pipe 13 which lies outside the borehole is provided with openings 14 for ejecting the excavated material.

By means of the core bit, an annular hole is cut into the layers of soil or rock to Ibe drilled through and the ybit is progressively advanced into said hole. The resulting core and the material removed from the annular hole enter the cavity of the bit and advance therein into the drill pipe until the material reaches the openings 14, through which it is ejected into the open.

It has been found in drilling through loamy soil, in hard rock or in layers of course gravel that the core material is disintegrated by the vibrations produced -by the percussions, and by the rotary movement of the drill pipe, and the material loses at least its coherence and falls in the form of pieces out of the openings in the end pipe. The core appears to follow in part the rotary movement of the drill pipe near the end of the latter.

When big stones are embedded in the layer to be drilled through, these stones can also be drilled through by the lcore drill. Whereas the drilling rate is slower in such large stones than in layers of coarse gravel or soil, it is not necessary to interrupt the method when such ya stone is encountered.

It may be desirable to line the borehole With a casing, which is introduced as the drilling proceeds and prevents the wall of the borehole from caving in. For this purpose, the cutter bit or a drill pipe is formed with a step so that a casing pipe can be pushed over the succeeding drill pipes and enters the borehole with the advancing drill pipes. When the dam has been drilled through, the casing pipe remains in the 4bore hole whereas the core bit and lthe drill pipes can be pulled out at the point of breakthrough.

What is claimed is:

1. Drilling equipment for drilling in a direction having a -generally horizontal component, said equipment comprising a cutter bit,

a string of drill pipes,

means for imparting rotary and percussive axial movement to said string of drill pipes operatively connected thereto, and means connecting said drill pipes to said cutter bit to impart said rotary and axial movement to said cutter bit, said connecting means being formed with apertures which communicate with the interior of said drill pipes Iand which are adapted to receive material Which has been detached by said cutter bit,

said connecting means being further adapted to subject said material in said lapertures to said percussive movement so as to cause said material to move through said apertures into and through said drill pipes,

said drill pipes being formed in a portion remote from said cutter bit With lateral openings for discharging said material out of said drill pipes.

2. Drilling equipment as set forth in claim 1, wherein said means for imparting rotary and axial movement to said string of drill pipes comprises a rot-ary motor for imparting said rotary movement to said drill pipes.

3. Drilling equipment as set forth in claim 1, in which said drill pipes have throughout their length approximately the same outside diameter as that portion of said bit which is largest in diameter.

4. Drilling equipment as set forth in claim 1, in which said connecting means comprise a shank connected between said drill pipes and said cutter bit which is formed with a peripheral bead for smoothening the borehole.

5. Drilling equipment as set forth in claim 1, which comprises a peripheral bead formed on said drill pipe closest to said cutter bit which is adapted to smoothen the borehole.

6. Drilling equipment as set forth in claim 1, in which said cutter bit constitutes a step bit and said connecting means comprise a shank formed with an annular groove, which is succeeded in the direction toward said drill pipe by a conically enlarged portion having approximately the same diameter as that portion of said bit Which is largest in diameter, and

means connecting said conically enlarged portion to said drill pipes and defining said apertures.

7. Drilling equipment as set forth in claim 6, in which said means defining said apertures comprise `webs.

8. Drilling equipment as set forth in claim 6, in which bladelike extensions are carried by said means dening said apertures and said extensions are adapted to push the detached material into the drill pipes through said apertures.

9. A method of drilling, in a substantially horizontal direction, through soil or rock by means of a rotary and percussion drill, comprising the steps of drilling into the soil or rock with a bit, thereby forming a borehole therein, extracting the borings from said borehole by means of the percussive and rotary action of said drill, via pipes having openings and being connected to said bit, and discharging the borings through said openings provided in said pipes.

10. The method for drilling as set forth in claim 9, including the step of smoothing and compacting the walls of said borehole by means of projection means provided on said drill.

11. The method for drilling as set forth in claim 10 including the step of Washing said borings by means of liquid conducted by pipe means through said pipes to said bit and exiting therefrom.

References Cited UNITED STATES PATENTS 629,539 7/1899 Bertram 175-215 X 1,678,201 7/ 1928 Samuelson 175-324 X 1,882,906 10/1932 Renfer 175-405 X 2,234,454 3/1941 Richter 175-215 2,816,737 12/1957 Kinard et al. 175-404 X 3,022,840 2/ 1962 Hohos et al. 175-213 X 3,154,158 10/1964 Lincoln 175-135 Re. 23,539 8/1952 Tilden 175-403 X CHARLES E. OCONNELL, Primary Examiner R. E. FAVREAU, Assistant Examiner U.S. Cl. X.R. -389 

